They described the workers’ veto as ridiculous and said it was ‘a policy that beggars belief’.

The incredulity among Islamic observers came as M&S chiefs issued an apology over the affair, in which shoppers at a London store were told to find another till when they tried to buy wine from a Muslim member of staff.

‘It’s ridiculous': Legal consultant Khola Hasan criticised Marks & Spencer after the chain allowed Muslim employees to excuse themselves from serving alcohol or pork. The store has since apologised over the affair

A spokesman for the Muslim Council of Britain said yesterday: ‘An employer can refuse Muslim employees permission to be excused from serving alcohol or pork because it would impact on customer service, as has happened in this case. Perhaps the solution should have been to deploy the Muslim employee who objected to serve alcohol or pork on tasks away from the till.’

The rights of staff to observe their religious beliefs in the workplace have drawn legal and political controversy over the past few years.

Christian workers who asked not to be made to conduct civil partnership ceremonies or to give sex advice to gay couples have been sacked, and judges have ruled that those who do not like their employer’s rules should find another job.

M&S store chiefs, however, told Muslim checkout workers they were entitled to abide by their religious belief that they should not handle alcohol or pork. A spokesman for the chain insisted yesterday that its rules put customer service first, adding: ‘We apologise that this policy was not followed in the case reported.’

M&S apologised after it emerged a Muslim check-out worker refused to serve a customer alcohol

An M&S spokeswoman said the store’s policy is that members of staff who cannot handle specific food or drink products, as a result of their religious beliefs are given a ‘suitable role’

Inayat Bunglawala (pictured) said: ‘I have never come across a Muslim.. who would refuse to serve a customer’

But the company found little sympathy among prominent moderate Muslim leaders yesterday.

Khola Hasan, a legal consultant who has advised the Islamic Sharia Council, told BBC Radio 4’s Today programme: ‘I was quite dismayed when I heard this news about M&S. I’m just wondering how far till workers can go? Are they there to police what people are buying?

‘Will a till worker refuse to process a cake that has got champagne in it or a chocolate that has got brandy in it?

‘Muslims cannot eat any meat that is not halal, so will they refuse to process chicken or beef or lamb because it’s not halal? I don’t know how far we are going to go. I think it’s ridiculous.’

Miss Hasan said that Islamic law does not prohibit Muslims from selling alcohol in a supermarket.

She added: ‘I think that we have to live together and that includes Muslims. How are we going to live together if we are sitting in a shop saying, “I won’t serve you and I won’t talk to you because you’ve got this in your hands?”.’

Inayat Bunglawala of Muslims4UK said: ‘I have never come across a Muslim in the retail trade who would refuse to serve a customer. If you are working in that trade, I don’t think anyone will hold it against you if you are working at a checkout and passing through cans of drink or packages of pig meat.’

M&S has faced a series of threats from customers who said they would take their business elsewhere rather than be told to wait for another till.

One shopper at the store involved said: ‘I had one bottle of champagne and the lady, who was wearing a headscarf, was very apologetic but said she could not serve me. She told me to wait until another member of staff was available. I was taken aback.’

The M&S statement said: ‘Customer service is our priority.

‘Where we have an employee whose religious beliefs restrict food or drink they can handle, we work closely with our member of staff to place them in a suitable role, such as in our clothing department or bakery.’